Polymersomes: Tough vesicles made from diblock copolymers

Science

Volumn 284, Issue 5417, 1999, Pages 1143-1146

  Discher, Bohdana M ^a   Won, You Yeon ^b   Ege, David S ^a   Lee, James C M ^a   Bates, Frank S ^b   Discher, Dennis E ^a   Hammer, Daniel A ^a  

^a UNIVERSITY OF PENNSYLVANIA   (United States)

^b University of Minnesota   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

COPOLYMER; POLYMER;

ARTICLE; ELECTROCHEMICAL ANALYSIS; MOLECULAR DYNAMICS; MOLECULAR STABILITY; MOLECULAR WEIGHT; PRIORITY JOURNAL; THERMOSTABILITY;

CHEMISTRY, PHYSICAL; LIPID BILAYERS; LIPOSOMES; MEMBRANES, ARTIFICIAL; MOLECULAR WEIGHT; OSMOTIC PRESSURE; PERMEABILITY; PHOSPHOLIPIDS; POLYETHYLENES; POLYMERS; SURFACE TENSION;

EID: 0033553661     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.284.5417.1143     Document Type: Article

References (39)

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18. Thin (about 10- to 300-nm) films of aqueous solution suspended in a microperforated grid were prepared in an isolated chamber with temperature and humidity control. The sample assembly was rapidly vitrified with liquid ethane at its melting temperature (≃90 K), and this was kept under liquid nitrogen until it was loaded onto a cryogenic sample holder (Gatan 626). We obtained images with a JEOL 1210 at 120 kV using a nominal underfocus of 6 μm and digital recording. For a more detailed description or related examples, see Z. Lin, M. He, L. E. Scriven, H. T. Davis, J. Phys. Chem. 97, 3571 (1993); A. Walter, P. K. Vinson, A. Kaplun, Y. Talmon, Biophys. J. 60, 1315 (1991).
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20. 37, synthesized by a combination of anionic polymerization and catalytic hydrogenation, was subsequently lyophilized into a solid and solubilized, when needed, in chloroform at 4 mg/ml. Evaporation of the solvent under nitrogen followed by vacuum drying for 3 to 48 hours was used to deposit a film on 1-mm-diameter platinum wire electrodes held in a Teflon frame (5 mm separation). The Teflon frame and electrodes were assembled into a chamber by sealing with coverslips, and this was subsequently filled with 100 mM sucrose solution. To begin generating vesicles from the film, we applied an alternating electric field to the electrodes (10 Hz, 10 V) while the chamber was mounted and viewed on the stage of an inverted microscope. Giant vesicles attached to the film-coated electrode were visible after 15 to 60 min. These were dissociated from the electrodes by lowering the frequency to 3 to 5 Hz for at least 15 min. The electroformation method is adapted from that of M. I. Angelova, S. Soleau, P. Meleard, J. F. Faucon, and P. Bothorel [Prog. Coll. Polm. Sci. 89, 127 (1992)], as previously used by M. L. Longo, A. J. Waring, and D. A. Hammer [Biophys. J. 73, 1430 (1997)]. The vesicles were stable for at least several days when kept sealed from air in a gas-tight, plastic syringe. Of additional note, vesicles were stable when resuspended in physiological saline at temperatures ranging from 10° to 50°C. Micromanipulation was done with micropipette systems analogous to those described by M. L. Longo et al. and D. E. Discher, N. Mohandas, and E. A. Evans [Science 266, 1032 (1994)].
21. 37, synthesized by a combination of anionic polymerization and catalytic hydrogenation, was subsequently lyophilized into a solid and solubilized, when needed, in chloroform at 4 mg/ml. Evaporation of the solvent under nitrogen followed by vacuum drying for 3 to 48 hours was used to deposit a film on 1-mm-diameter platinum wire electrodes held in a Teflon frame (5 mm separation). The Teflon frame and electrodes were assembled into a chamber by sealing with coverslips, and this was subsequently filled with 100 mM sucrose solution. To begin generating vesicles from the film, we applied an alternating electric field to the electrodes (10 Hz, 10 V) while the chamber was mounted and viewed on the stage of an inverted microscope. Giant vesicles attached to the film-coated electrode were visible after 15 to 60 min. These were dissociated from the electrodes by lowering the frequency to 3 to 5 Hz for at least 15 min. The electroformation method is adapted from that of M. I. Angelova, S. Soleau, P. Meleard, J. F. Faucon, and P. Bothorel [Prog. Coll. Polm. Sci. 89, 127 (1992)], as previously used by M. L. Longo, A. J. Waring, and D. A. Hammer [Biophys. J. 73, 1430 (1997)]. The vesicles were stable for at least several days when kept sealed from air in a gas-tight, plastic syringe. Of additional note, vesicles were stable when resuspended in physiological saline at temperatures ranging from 10° to 50°C. Micromanipulation was done with micropipette systems analogous to those described by M. L. Longo et al. and D. E. Discher, N. Mohandas, and E. A. Evans [Science 266, 1032 (1994)].
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39. We thank E. A. Evans, D. Needham, P. Nelson, and T. Lubensky for discussions. Support was primarily provided by the NSF-supported Materials Research Science and Engineering Center (MRSEC) at the University of Pennsylvania (DMR96-32598) and both the Center for Interfacial Engineering (CIE) and the MRSEC (DMR 98-09364) at the University of Minnesota. The work was also supported in part by grants from the Whitaker Foundation (D.D.) and National Institutes of Health [R01-HL62352-01(D.D.) and P01-HLI8208 (D.H.)].